You've probably been getting a Pap test for years . . . but do you know why?

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To do the Pap test, your doctor or nurse scrapes a small sample of cells from your cervix and sends it to a laboratory. A technologist then looks at the cells under a microscope for signs of abnormal changes. The Pap test was developed in 1943 by Dr. George Papanicolaou. Thanks to its regular use since then, many women who need treatment are identified early, causing cervical cancer to drop from the second-leading cause of cancer deaths among American women to the 15th. However, it hasn't eliminated cervical cancer. In fact, more than 11,000 American women still get cervical cancer every year. In this section, you'll learn why.

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What are the possible results from a Pap test?

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When your doctor's office informs you of the result of your Pap test, you will likely be told your Pap was normal, abnormal or "borderline" (often called an ASC-US Pap).

Pap Test Result

What It Means

Normal

Your cervical cells appear to be healthy.

Abnormal*

There appear to be changes in your cervical cells that need to be examined further.

Borderline or inconclusive (officially called "ASC-US," which stands for atypical squamous cells of undetermined significance)

Your cervical cells are not obviously normal, but they are not clearly abnormal either.

* Note that when the lab reports the results of a Pap test as abnormal, it may use the terms LSIL or HSIL. LSIL (low-grade squamous intraepithelial lesion) is the term for abnormal cell changes that are mild and likely to go away on their own, without treatment. HSIL (high-grade squamous intraepithelial lesions) refers to cell changes that are moderate or severe and should be removed.

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How accurate is the Pap test?

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The Pap test can identify many women in need of treatment, especially when it is repeated regularly. However, the Pap is not foolproof. One recent study published in the Journal of the National Cancer Institute found that about one-third of cervical cancers occur due to Pap failure. In other words, these women's Pap results appeared normal, despite the slowly developing abnormal cells on their cervix. Even with the newer, "liquid-based" Pap, abnormal cells may be missed. [For more information on the JNCI study, refer to "Cervical Cancer in Women with Comprehensive Health Care Access: Attributable Factors in the Screening Process," by Wendy A. Leyden et al: Journal of the National Cancer Institute;Vol. 97, No. 9; May 4, 2005; pgs. 675-683.]

As a result, "false negative" results are possible from a Pap test. This means you are told your Pap is normal, when abnormal cells that could cause problems actually exist. For example, a false negative Pap may occur when the sample being examined does not contain enough cervical cells. Abnormal cells also may be hard to see if they are "hidden" by mucous or inflammation in the cervix. Or, signs of abnormal cells may simply be missed by the laboratory technologist when looking through the microscope.

A recent study in the Journal of the National Cancer Institute found that the Pap is particularly less accurate in detecting abnormal cells associated with a specific type of cervical cancer called "adenocarcinoma," which has become more common in recent years. The authors concluded that the use of routine HPV testing has the potential to reduce the occurrence of this type of cancer. [For more information on this study, refer to "Worldwide Human Papillomavirus Etiology of Cervical Adenocarcinoma and Its Cofactors: Implications for Screening and Prevention," by Xavier Castellsague et al: Journal of the National Cancer Institute;Vol. 98, No. 5; March 1, 2006; pgs. 303-315.]

Pap tests also may be "false positive." This means a woman is told that her cervical cells look abnormal when they are actually healthy. This can cause anxiety and lead to unnecessary tests and procedures.

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What is the HPV test?

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QIAGEN developed the first FDA-approved test to detect the presence of high-risk (cancer-causing) types of HPV. The digene HPV Test, which uses the company’s proprietary Hybrid Capture® 2 (hc2) technology, was approved by the U.S. Food and Drug Administration (FDA) in 1999 for follow-up evaluation of women whose Pap results are inconclusive ("ASC-US"), allowing healthcare providers to determine whether they need further examination. In 2003, the digene HPV Test was approved for routine use along with a Pap for all women 30 years of age and older, the group considered most at risk of cervical cancer.

The digene HPV Test uses computerized, molecular technology to determine whether you have one or more types of the HPV virus that cause cervical cancer. It works by detecting the genetic (DNA) "footprint" of the virus. When your doctor or nurse sends your sample of cervical cells to the laboratory for the Pap test, he or she can ask that the HPV test be done as well.

For full medical and technical information on The digene HPV Test click here (PDF).

In older women who are most at risk of developing cervical cancer (age 30+), screening has repeatedly been shown to be more accurate when the HPV test is done along with the Pap than when the Pap smear is used alone.

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How is the digene HPV Test done? Does it require any additional procedures?

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The digene HPV Test can be done by most laboratories, usually using the same sample of cervical cells collected for the Pap. It does not require any additional time or discomfort on your part.

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When is it appropriate for women under the age of 30 to have an HPV test as well as the Pap?

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When your doctor's lab is unable to tell whether your Pap is normal or abnormal, the HPV test can determine quickly if you have a high-risk type of the virus and thus need further examination to catch any abnormal cells that need treatment. Without the HPV test, you would have to wait several months and then repeat the Pap. For many women, this wait is a very anxious time. In addition, Pap results can sometimes be incorrect.

Special note for girls under 20: The consensus guidelines published in the October 2007 issue of the American Journal of Obstetrics & Gynecology do not recommend HPV testing at all for adolescents. This is because HPV infections are very common in sexually active girls, but cervical disease is very rare. Thus, the guidelines recommend that adolescents who have Pap smears that are inconclusive be re-tested with another Pap in 12 months. If the second Pap suggests the presence of pronounced cervical disease, a colposcopy exam is recommended. If not, the guidelines say a third Pap should be done in another year (24 months after the first Pap). If the Pap result does not appear normal at that point, a colposcopy should be performed (even if the Pap is still just "inconclusive").

Women under 30 are indeed sometimes diagnosed with cervical cancer despite having normal Pap results. However, it is relatively rare. While HPV infection is very common in young women, it usually goes away on its own or is suppressed by the body before it causes any problems. That means that if younger women were tested routinely, many would be found to have HPV and thus – even though the infection is most likely temporary – they might undergo additional, unnecessary procedures. It's a bit like mammography. Although young women sometimes get breast cancer, regular mammograms are not recommended until they reach the age of 40, when the risk is significant enough to justify regular monitoring.

Both the American College of Obstetrics & Gynecology (ACOG) and the American Cancer Society (ACS) recommend against routine testing for HPV under the age of 30.

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What are the possible results of the digene HPV Test?

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The digene HPV Test will either tell you that you have one or more high-risk types of HPV, or that you don't. If the test shows you have high-risk HPV, and you are at least 20 years old, the guidelines recommend that your doctor or nurse should perform an additional examination (colposcopy) to determine if abnormal cells are present that need to be removed.

Can the digene HPV Test tell what type of the virus you have?

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The digene HPV Test, the first FDA-approved HPV Test, tells you and your healthcare provider whether you have one or more high-risk types of the virus. However, although the test does not tell you which of those types you have, the extra exams and other follow-up care you should get if you have a form of high-risk HPV is currently the same no matter what strain you have. Here's a little background: There are about 15 types of high-risk HPV that can cause cervical cancer. Of those, 13 are considered the most important, and are known by the numbers assigned to them (in the order of their discovery): 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59 and 68. [There are more than 100 different types of HPV all together.]

Of these 13 types of high-risk HPV, two of them – 16 and 18 – have been shown to cause 70 percent of all cervical cancers. As a result, QIAGEN and other companies are developing additional tests that can determine which specific type(s) of HPV are present. These tests are currently available only in research labs.

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How accurate is the digene HPV Test?

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Although no test is perfect, the digene HPV Test is less vulnerable to error than the Pap. Studies show that, on average, the combination of the digene HPV Test and the Pap identifies 95-100 percent of women who are later confirmed to have advanced cervical disease (CIN 2, CIN 3 or cancer).

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How accepted is the HPV test as part of cervical cancer screening?

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The American College of Obstetricians and Gynecologists (ACOG), the American Cancer Society (ACS) and the American Society for Colposcopy and Cervical Pathology (ASCCP) all officially recognize the advantages of HPV testing for follow-up evaluation of women age 20 or older whose Pap results are inconclusive (ASC-US), as well as for routine use (along with the Pap) for women 30 and older. Follow-up HPV testing for women with inconclusive Paps is practiced by the vast majority of physicians and nurses providing gynecologic care. However, since it can take a while for healthcare professionals to make changes in the way they practice medicine, women age 30 and older often need to ask their doctors or nurses to order the HPV test along with their Pap regardless of their Pap result.